1. Field of the Invention
This invention relates to a formation method of a metal surface thin film which forms a metal surface thin film having high corrosion resistance and high adhesion by a physical or chemical vapor deposition method.
2. Description of the Prior Art
Heretofore, when a metal film of a different material from a metal substrate is formed on the surface of the metal substrate, it has been customary in the past to select a metal film made of a material having a lower spontaneous electrode potential than the metal substrate in order t prevent electrical corrosion.
In the formation of such a metal film, however, it has been necessary to select a material suitable for the metal substrate and when the metal substrate is made of a material having a low spontaneous electrode potential (for example, Al), a corrosion-resistant metal film cannot be formed on the surface of the metal substrate. If any pin-holes or the like exist on the metal film and reach the surface of the metal substrate, electrical corrosion develops from the pin-hole portions, because the metal film is in contact with the surface of the metal substrate.